Carboxylic acids (such as acetic acid, etc.) and derivatives thereof (such as methyl methacrylate, etc.) are produced industrially by use of carbonylation reactions. For example, Japanese Patent Application Laid-open No. 54011/1973 (JP-48-54011A) discloses a carbonylation method in which an olefin, an alcohol or ester thereof, a halide, or ether derivative is allowed to react in the liquid phase with carbon monoxide in the presence of a catalytic system containing a rhodium or iridium component and an iodine or bromine component. In this process, at least part of the liquid reactants is passed without heating through a separation zone that is substantially low in pressure to vaporize at least part of an above-mentioned carbonylation product, the vaporized carbonylation product is taken out, and the residual liquid reactants are recirculated to the above-mentioned reaction zone. With this literature, the removal of unreacted carbon monoxide from the reactor is indicated. Japanese Patent Application Laid-open No. 321847/1994 (JP-6-321847A) indicates a carbonylation product recovery method in which an iridium catalyst is used as the carbonylation catalyst, a vapor component containing the carbonylation product and a liquid component containing the iridium catalyst are generated by vaporization of the reaction product, the vapor component and the liquid component are separated, and the concentration of water in the liquid component is maintained at least at 0.5 weight %. With this literature, the discharge of unreacted carbon monoxide as exhaust gas from the reactor is illustrated.
Japanese Patent Application Laid-open No. 508594/1998 (JP-10-508594A) proposes a method comprising a first region, in which a carboxylic acid is produced by liquid phase carbonylation in the presence of a rhodium catalyst, and a second region, in which the reaction mixture is partially vaporized, and wherein a vapor fraction containing the produced carboxylic acid is refined and the non-vaporized liquid fraction containing the catalyst is circulated to the first region, carbon monoxide is added to the non-vaporized liquid fraction generated from the second region with preventing return of carbon monoxide to the second region to avoid loss of carbon monoxide.
However with such carbonylation reactions, the temperature and pressure of the reaction system fluctuate or vary with the circulation of the high boiling point component to the reaction system, causing the carbon monoxide consumption rate or usage rate of the reaction system to fluctuate and thus making the stabilization of the reaction system difficult. Also, the carbon monoxide discharge rate increases in accompaniment with the supplying of excess carbon monoxide and fluctuation of the carbon monoxide consumption rate of the reaction system. Carbon monoxide therefore could not be used effectively in the carbonylation reaction.
Japanese Patent Application Laid-open No. 95723/2000 (JP-2000-95723A) discloses a control method for a process of producing acetic acid by carbonylation, wherein the flow of carbon monoxide that passes through a control valve is measured, the average value of the carbon monoxide flow within a predetermined term is calculated, a fixed value is added to this average carbon monoxide flow to calculate the maximum flow rate of carbon monoxide, and operation is performed so that the flow rate of carbon monoxide into the reactor will not exceed the maximum flow rate. With this method, since the carbon monoxide flow rate is controlled using a maximum flow rate, determined by adding a fixed value to the average carbon monoxide flow, as a reference, it is difficult to suppress fluctuations of the temperature and pressure of the reaction system and thereby stabilize the reaction system.
Thus an object of the present invention is to provide a reaction control method (or stabilization method) and a reaction control apparatus (or stabilization apparatus) by which a liquid phase reaction system, such as a carbonylation reaction system, can be stabilized effectively.
Another object of the present invention is to provide a reaction control method (or stabilization method) and a reaction control apparatus (or stabilization apparatus) with which the temperature and pressure fluctuations of a liquid phase reaction system are controlled to enable stable production of products in an industrially advantageous manner.